-LRB- CNN -RRB- -- It 's become a go-to tool for journalists , a digital man-on-the-street interview when big news breaks : see what they 're saying on Twitter .

There 's just one problem with that , says the Pew Research Center . Opinions expressed in the rapid-fire Twitter echo chamber , particularly in response to political news , are often at odds with the general public 's .

The differences ? Sometimes Twitter is more liberal . At other times , it 's more conservative . And it 's very nearly always more negative .

`` Overall , the reaction to political events on Twitter reflects a combination of the unique profile of active Twitter users and the extent to which events engage different communities and draw the comments of active users , '' the report reads . `` While this provides an interesting look into how communities of interest respond to different circumstances , it does not reliably correlate with the overall reaction of adults nationwide . ''

In the yearlong study , Pew focused on political events such as the result of the 2012 presidential election , the first presidential debate between President Barack Obama and challenger Mitt Romney and several speeches given by Obama .

Some examples : When Obama won re-election , public opinion polls suggested 52 % of the public was pleased and 45 % unhappy . On Twitter , a full 77 % of tweets about his win were positive and only 23 % negative .

Similarly , only 20 % of the public told pollsters they thought Obama did a better job than Romney in their first debate -LRB- the one in which Obama was criticized for looking tired and unfocused -RRB- . But 59 % of tweets favored him .

Part of that might be explained by looking at who uses Twitter .

Pew 's research shows that Twitter users are considerably younger than the general public and more likely to lean Democratic . In a 2012 survey , half of adults who said they posted news on Twitter were younger than 30 , compared with 23 % of all adults .

And 57 % of those who posted news on Twitter were either Democrats or leaned Democratic , compared with 46 % of the general public .

But Twitter pundits do n't always lean to the left .

Nearly half of the U.S. public -LRB- 48 % -RRB- thought Obama did a good job on his second inaugural address . But only 13 % of the tweets about it echoed that opinion .

Opinions about Sen. John Kerry being nominated as Obama 's secretary of state split the general public : 39 % approved , 36 % disapproved and 26 % had no opinion . On Twitter , a measly 6 % expressed support , while 32 % were negative and a clear majority , 62 % , expressed no opinion .

The reason for such a swing , Pew said , is that on Twitter , unlike in opinion polls , users decide what they think is important enough to mention publicly . A generally popular event might not be portrayed that way if an angry minority is more inspired to post about it .

For example , nearly 14 million wrote on Twitter about Obama 's re-election while a mere 70,000 remarked on Kerry 's nomination .

Politics also reflect a truth that anyone who 's followed the Oscars , Super Bowl , debate nights or , really , any public event can attest to -- the Twitter universe is never happier than when it 's being snarky , or downright nasty , to someone .

`` The overall negativity on Twitter over the course of the campaign stood out , '' Pew writes . `` For both candidates , negative comments exceeded positive comments by a wide margin throughout the fall campaign season . ''

There were more negative than positive comments about Obama and Romney on Twitter . The negative comments about Obama bounced back and forth between 40 % to 50 % throughout the campaign , while positives went up to about 30 % and down into the teens . -LRB- Remember , lots of comments can be neutral -RRB- .

Romney 's negatives were higher . Usually , between 50 % to 60 % of talk about him was not nice , while positives only broke above 20 % during the campaign 's final days .

Another thing to keep in mind when monitoring the conversation on Twitter : While it seems to be omnipresent among the digitally connected -LRB- yes , like we journalists tend to be -RRB- , its overall reach is modest compared to other media .

In the Pew 's 2012 news consumption survey , just 13 % of adults said they ever use Twitter or read Twitter messages . Only 3 % said they regularly or sometimes tweet or retweet news or news headlines on Twitter .

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Study : Twitter opinions rarely reflect those of the general public

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Pew Research says the most significant difference is that Twitter 's more negative

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Twitter users are younger than the public and more identify as politically liberal

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But during some events , the site skewed too conservative vis-a-vis opinion polls